The present disclosure relates to image forming apparatuses.
Known image forming apparatuses include those configured so that an electrostatic latent image is formed on the peripheral surface of a photosensitive drum, the formed electrostatic latent image is developed by supply of toner from a developing roller, and the toner image is transferred to a given sheet material. In such an image forming apparatus, generally, a photosensitive drum, a developing roller, and their surrounding elements are integrated into a single or plurality of units and designed to be capable of being pulled out of the apparatus body unit by unit, resulting in improved efficiency of maintenance work and assembly work.
Meanwhile, a developing unit including a developing roller is generally constructed with the developing roller facing a photosensitive drum through gap rollers between them, is urged toward the photosensitive drum by a pressure spring to press the gap rollers against the photosensitive drum, and thus maintains a constant distance between the developing roller and the photosensitive drum. Therefore, in pulling the developing unit out of the apparatus body, a separating mechanism is necessary which can completely separate the developing roller from the photosensitive drum.
For example, the following developer supporting device is known as such a separating mechanism which can separate the developing unit from the photosensitive drum. The developer supporting device is configured to support on a fixed frame a carriage body, which is normally held at a position to install a developer by an urging device, movably in a direction perpendicular to the axis of the photosensitive drum (horizontal direction). With the use of the developer supporting device, when the carriage body is moved against the urge of the urging device, the developing roller can be separated completely from the photosensitive drum and thus the developing unit can be pulled out of the apparatus body.